The advantages of using blades with a slicing rather than chopping motion have been known for hundreds, perhaps thousands of years. One has but to cut a loaf of bread to immediately realize that a slicing motion cuts cleaner and with less tearing. The most immediate advantage for the blade is the reduction of force that is required for cutting, reducing wear and tear on the cutting edge. For a shaver, it is perhaps more important that the cutting force applied to the follicles be reduced, producing a less painful shaving experience. While it has been possible for the shaver to use straight razors, as well as disposable razor cartridges, in such a way as to create an oblique or slicing angle, this has always been hazardous, as the blade that easily slices follicles also easily slices the epidermis. Several patents have resulted from attempts to safely apply the advantages of a slicing angle to shaving. Gordon, (U.S. Pat. No. 3,964,160) and Copelan, (U.S. Pat. No. 5,526,568) patented razors which made manual oblique shaving easier, that is, the wrist did not have to be held at an awkward angle to maintain the slicing angle, but both lacked the concomitant stability of a razor head perpendicularly oriented to the shaving direction. Copeland teaches that, to obtain the advantages of oblique shaving while avoiding cutting of the skin, the oblique angle of a useable razor head should be restricted to between 10 and 26 degrees, and preferably to an angle of 18 degrees. Razors featuring adjustable slicing angles, such as Gordon's, have had an additional disadvantage, since the geometry of the razor head must be carefully balanced, and is unlikely to be optimum for variable slicing angles. Others have patented a variety of oblique arrangements, wherein a pair of blades are oriented in a "V" arrangement. Carroll (U.S. Pat. No. 1,241,921), Moody (U.S. Pat. No. 228,829), and Browning (U.S. Pat. No. 1,387,465) are typical of this approach, which suffers from excess stability. Because of the large footprint created by the two legs of the cutting zone, such a razor head has great difficulty in handling variations in facial geometry; a difficulty which only increases as the slicing angle, is increased. Savage (U.S. Pat. No. 4,663,843) patented a razor head using a conventional blade in tandem with blades angled at a slicing angle. He teaches that the slicing angle should lie between 15 and 30 degrees, in order to have some of the advantages of oblique cutting, while avoiding cutting of the skin. Savage does not appreciate the advantages arising from the use of intrinsic fencing, which would not only allow shaving at much higher slicing angles, but also make a tandem conventional blade unnecessary.
Fencing of razor blades is known. Dickenson (U.S. Pat. No. 1,035,548) teaches the use of wire wrapping of the blade edges, an approach that has been used by several others, such as Iten (U.S. Pat. No. 3,505,734), and Michelson (U.S. Pat. No. 3,750,285). Similarly, Ferrara (U.S. Pat. No. 3,263,330) discloses a fencing arrangement wherein the blade edge is wrapped with a flexible perforated sheet, and Auton (U.S. Pat. No. 4,252,837) patented a blade fenced with a vacuum deposited intermittent coating. Galligan et al. (U.S. Pat. No. 4,914,817) teaches the use of tape having parallel riblets covering parts of the blade edges. None have previously appreciated the advantages accruing from intrinsically fenced blades.
Foil blades are known. Ackerman (U.S. Pat. No. 2,794,252) patented a perforated foil blade arrangement claimed to enable omni-directional shaving. Brown (U.S. Pat. No. 5,153,992) patented a perforated blade wherein shaving could be accomplished with a "scrubbing action". Perforated blades do not benefit from the advantages inherent in a single high slicing angle.
Ceramic blades are also known. Hahn (U.S. Pat. No. 5,048,191) teaches the production of ceramic blades using abrasive and sputtering steps, while Trotta (U.S. Pat. No. 5,018,274) patented a razor head produced from a obliquely sliced ceramic billet containing rectangular cells. The Trotta approach requires a considerable amount of polishing of small cut parts.